This invention relates to essentially amorphous, non-chlorinated polymeric films and to the use of such films as effective barriers to odors and organic molecules.
Multilayer structures, which are substantially impervious to gases and/or moisture, are well known in the medical and food packaging industries. Currently, poly(vinylidene chloride) (PVDC) is used as one of the materials of choice for the gas barrier component of barrier films. For ostomy applications (i.e., colostomy and ileostomy), a film of PVDC sandwiched between opposing layers of low density polyethylene (LDPE) is widely used, with PVDC functioning as the gas barrier, and LDPE as the structural and sealant layer. Also, polyvinyl chloride (PVC) or chlorinated polyethylene (CPE) blended with ethylene-vinyl acetate copolymer (EVA) can be used in the structural and sealant layer, or other layers, of such a structure.
However, disposal of these chlorine-containing materials presents a number of potential environmental concerns, especially relating to incineration of these materials after use in hospitals or otherwise. In addition, exposure to di-2-ethylhexyl-phthalate (DEHP), a common plasticizer utilized with PVDC and PVC, may present a number of health-related concerns, including reduced blood platelet efficacy, and potential links to liver cancer.
Non-chlorine containing polymeric resins, such as ethylene-vinyl alcohol copolymers (EVOH), are also used as barrier layers and have been suggested for ostomy applications. However, while the barrier properties of EVOH copolymers are very high under dry conditions, they rapidly deteriorate in the presence of moisture. Thus, EVOH copolymers are not desirable for ostomy applications.
U.S. Pat. No. 5,496,295, U.S. Pat. No. 5,658,625 and U.S. Pat. No. 5,643,375 describe multilayer barrier films and articles made thereof. These films are useful, among others, in ostomy applications, and comprise a gas barrier layer of a chlorine-free organic polymer, which is substantially impermeable to oxygen gas, and a moisture barrier layer of a mesophase propylene-based material. The chlorine-free organic polymer gas barrier layer includes vinyl alcohol polymers, such as EVOH copolymers, polyvinyl alcohol (PVOH), polyacrylonitrile, polystyrene, polyester and nylon either alone or blended with each other. The moisture barrier layer comprises a mesophase propylene polymer-based material, such as mesomorphous polypropylene, mesopolymer blends and/or mesocopolymers. Quenching a propylene-based material from the melt state forms the mesophase propylene-based material.
EP 0 700 777 A1 describes a chlorine-free multilayer film useful for manufacturing bags or pouches for ostomy/urostomy applications and comprising a seven layer structure. This structure comprises a gas barrier layer of a chlorine-free organic polymer which is substantially impermeable to oxygen, such as one of the above vinyl alcohol polymers, polyamides, polyesters and polystyrenes; two tie layers each contacting one side of said barrier layer; an inner surface layer; an outer surface layer and two intermediate layers positioned between said surface layers and comprising an ethylene-propylene (EP) copolymer.
EP 0 418 836 A3 describes multilayer oriented films suitable for use in the food packaging industry and having layers of a propylene homopolymer or copolymer, a co-polyester layer and an adhesive layer of a polar-modified polyolefin located between, and bonded to, the propylene polymer and co-polyester layers.
EP 0 056 323 A1 describes a thermoformable laminate for a sterilizable packaging comprising a cast layer of polyester, including polybutylene terephthalate, glycol-modified polyethylene terephthalate (PET-G), and a copolymer of cyclohexane dimethanol and terephthalic acid, joined by a bonding layer consisting of polypropylene (PP), LDPE or an ionomer resin. However, since such structures are targeted for thermoformable packaging applications, they possess high modulus and, therefore, cannot provide the required level of quietness needed for ostomy bag application as a result of the relatively rigid polymers used for skins composition. Additionally, the Tangent Delta (Tan xcex94) value of the skin polymers (LDPE, crystalline PP and ionomer resins) of these laminates indicate that they do not provide a quiet film as described below.
EP 0 588 667 A2 describes a multilayer film useful in moisture barrier packaging applications having at least one layer comprising a blend of propylene polymer or copolymer and a hydrocarbon resin and two additional layers comprising a propylene homopolymer or copolymer, an ethylene-alpha-olefin (EAO) copolymer, an ionomer, polybutylene or blends thereof. A core layer of an EVOH copolymer or another oxygen barrier material or high density polyethylene (HDPE) can be included in some embodiments.
Attempts to find additional chlorine-free polymeric films suitable for use as barrier layers have been guided by a generally held belief that a polymer having good oxygen barrier properties would also exhibit good barrier properties to organic products and odors. (See, for example, xe2x80x9cPlastic Film Technology, High Barrier Plastic Films for Packagingxe2x80x9d, volume 1: The use of Barrier Polymers in Food and Beverage Packaging, M. Salame, pp. 132-145 (1989)). Therefore, attempts to find polymeric films with sufficient barrier properties for use in the medical and food-packaging industries have focused upon the oxygen permeability of a given polymeric film. However, the inventors of the present application have found that not all polymers having low oxygen permeability exhibit odor barrier properties sufficient for ostomy applications and vice versa.
Studies have shown that human feces contain more than 122 volatile compounds as analyzed by gas chromatography/mass spectrometry. (See xe2x80x9cIdentification of Specific Trace Levels of Chemicals in Human Fecesxe2x80x9d, Dmitriev M. T., Lab. Delo (1985), (10), 608-14; xe2x80x9cGas-Chromatographic and Mass-Spectrometric Analysis of the Odour of Human Fecesxe2x80x9d, J. G. Moore, Gastroenterology, 1987, 93, 1321-9; M. D. Levitt, xe2x80x9cOnly the Nose Knowsxe2x80x9d, Gastroenterology, 1987, vol. 93, No. 6, 1437-8; xe2x80x9cInfluence of Nutritional Substrates on the Formation of Volatiles by the Fecal Floraxe2x80x9d, M. Hiele, Gastroenterology, 1991, 100, 1597-1602; xe2x80x9cScreening Method for the Determination of Volatiles in Biomedical Samplesxe2x80x9d; Y. Ghoos, Journal of Chromatography, 665, 1994, 333-345; and xe2x80x9cInfluence of Dietary Protein Supplements on the Formation of Bacterial Metabolites in the Colonxe2x80x9d, B. Geypens, GUT, 1997, 41, 70-76.)
These studies indicate that compounds responsible for fecal odor are mainly indoles and sulfide derivatives. Thus, compounds having relatively small molecules, such as, for example, hydrogen sulfide (H2S) or methyl mercaptan (CH3SH), compounds having larger molecules, such as, for example, ethyl sulfide, dimethyl disulfide (DMDS) or diethyl disulfide (DEDS), and compounds having large molecules, such as, for example, dimethyl trisulfide, indole or 3-methyl indole, are responsible for fecal odor.
Therefore, there remain needs in the art for polymeric films which (a) are environmentally safe, (b) are hydrolytically stable, and (c) exhibit low permeability to both small and larger molecular diameter odor-causing molecules. Furthermore, depending upon the end-use of such films, there remains the need for these films to be quiet, i.e., having low noise emission when crumpled.
Those needs are met by the present invention. Thus, the present invention provides essentially amorphous, non-chlorinated (or chlorine-free) polymer films useful as barriers to odors and organic compounds, as well as methods of using such films as barriers to odors and organic molecules in a monolayer or a multilayer film structure.
A first embodiment of the present invention is an essentially amorphous, non-chlorinated polymer film, the film functioning as a barrier to at least one of odors and organic molecules that have a diameter of 0.40 nanometer (nm) or more (xe2x89xa7) with barrier functionality being determined by at least one of a) a 3-methyl indole breakthrough time of at least(xe2x89xa7) five hours, b) a DEDS breakthrough time of at least 40 minutes (min) or c) a H2S permeation rate less than or equal to (xe2x89xa6) 60 cubic centimeters (cm3) of H2S per square centimeter (cm2) of film area per day (cm3/cm2-day), as well as a method of using such films as barriers to odors and organic molecules in either a monolayer or a multilayer film structure.
A second embodiment provides multilayer film structures containingxe2x89xa7one layer of the film of the first aspect and xe2x89xa7one quiet film layer that has reduced noise emission, said quiet film layer comprising xe2x89xa6one polymeric resin or polymeric resin composition having a Tan xcex94 value xe2x89xa70.25 at a temperature within the range between xe2x88x925xc2x0 centigrade (xc2x0 C.) and 15xc2x0 C., or xe2x89xa70.32 at a temperature within the range of from xe2x88x9212xc2x0 C. to xe2x88x925xc2x0 C. The multilayer film structures desirably function as barriers to molecules having a diameterxe2x89xa70.40 nm.
A third embodiment provides a method of reducing the emission of noise in a multilayer film structure containingxe2x89xa7one layer of the film of the first embodiment, the method comprising the steps of: a) blending a first polymer resin, polymer resin composition or polymer blend composition having a Tan xcex94 value xe2x89xa70.25 at a temperature within the range between xe2x88x925xc2x0 C. and 15xc2x0 C. or xe2x89xa70.32 at a temperature within the range of from xe2x88x9212xc2x0 C. to xe2x88x925xc2x0 C. with a second polymer resin; and b) forming a polymer film layer of the multilayer film from the blended polymer resins, wherein the first polymer resin or polymer resin composition comprises xe2x89xa725 percent by weight (wt %), based on total layer weight.
The polymeric barrier films of the present invention are particularly useful for ostomy bags (colostomy, ileostomy), trans-dermal delivery systems (TDDS), cosmetic patches, incontinence bags, medical collection bags, parenteral solution bags, and packaging of odorous food or products, as well as for protective clothing applications or soil fumigation.
As stated above, the present invention provides essentially amorphous, non-chlorinated polymer films, which are useful as barriers to odors and organic compounds, as well as methods of using such films, in a monolayer or multilayer film structure, as barriers to odors and organic molecules.
As used herein, xe2x80x9cessentially amorphousxe2x80x9d means containing less than ( less than ) 8 wt % non-amorphous polymer(s), based on total polymer weight. Moreover, it refers to amorphous polymers that have not been prepared through quenching. xe2x80x9cQuenchingxe2x80x9d, as used herein, means rapid cooling of the polymer from its melt state down to a sub-ambient temperature (below approximately 20xc2x0 C.). xe2x80x9cNon-chlorinatedxe2x80x9d means that a polymer contains substantially no chlorine (i.e.,  less than 1 wt %, based on total polymer weight).
The terms xe2x80x9crelatively smallxe2x80x9d, xe2x80x9clargerxe2x80x9d and xe2x80x9clargexe2x80x9d molecules, as used herein, refer to relative sizes as determined by respective critical molecular diameter (CMD). xe2x80x9cRelatively smallxe2x80x9d molecules include molecules having a CMD of 0.40 nm up to 0.55 nm. xe2x80x9cLargerxe2x80x9d molecules include molecules having a CMD of more than ( greater than ) 0.55 nm and up to 0.70 nm, and xe2x80x9clargexe2x80x9d molecules include molecules having a CMD  greater than 0.70 nm.
The calculated CMD of oxygen is 0.33 nm, 0.40 nm for H2S, 0.50 nm for methyl sulfide, 0.55 nm for DMDS, 0.57 nm for ethyl sulfide, 0.58 nm for DEDS, 0.63 nm for dimethyl trisulfide, 0.74 nm for indole and 0.78 nm for 3-methyl indole. CMD determination uses a SPARTAN 5.1.1. program (molecular orbital program marketed by WAVEFUNCTION Inc., California 92612, USA).
Molecular structures are optimized by energy minimization using semi-empirical quantum mechanics models (AM1 method: M. J. S. Dewar, E. G. Zoebisch, E. F. Healy, and J. J. P. Stewart, J. Am. Chem. Soc. 107, 3902 (1985). AM1: A New General Purpose Quantum Mechanical Molecular) contained in the Spartan program version 5.1.1. Conformational analysis is carried out in order to obtain structures in their minimum-energy conformations. The CMD is obtained from the space-filling (CPK) representation of the optimized structure. The box size is adjusted in order to contact the van der Waals spheres. The molecular diameter is taken as the second-largest box dimension.
However, while a given polymeric film""s low oxygen permeability may be a reasonable predictor of the polymeric film""s low permeability to the smaller odorous molecules in human fecal matter, such as H2S and CH3SH, such permeability may not be a reasonable predictor of the polymeric film""s permeability to larger molecules, such as DEDS and 3-methyl indole. Hence, the inventors of the present application believe that a given polymeric film""s low oxygen permeability does not provide a reasonable predictor of the usefulness of the polymer film in ostomy applications. The permeabilities to H2S, DEDS and 3-methyl indole are selected to predict the odor barrier performance in ostomy applications, as these three compounds represent the main chemical families of odorous compounds found in feces, and cover a range from relatively small to large molecule sizes.
In the present invention, it has been found that polymer films that function as a barrier to molecules having a CMD xe2x89xa70.40 nm can be formed from, but are not limited to, polymeric resins pertaining to Polymer List I. Polymer List I comprises: polymethyl methacrylates (PMMA), PET-G, an amorphous thermoplastic co-polyester resin (e.g. B-100 resin supplied by Mitsui Chemicals Europe GmbH) (hereinafter referred to as xe2x80x9cAPE-1xe2x80x9d), blends of PET-G and such an amorphous thermoplastic co-polyester resin, blends of PET-G and a styrene-butadiene copolymer (PET-G/SB), blends of PET-G and a styrene-butadiene-styrene block copolymer (PET-G/SBS), blends of PET-G and a maleic anhydride (MAH) grafted ethylene-methyl acrylate copolymer (PET-G/MAH-g-EMA), blends of PET-G and an ethylene-methyl acrylate-glycidyl methacrylate copolymer, blends of PET-G and a MAH functionalized styrene-ethylene-butene-styrene (PET-G/SEBS) block copolymer, blends of PET-G and a styrene-isoprene-styrene (PET-G/SIS) block copolymer, and amorphous thermoplastic polyester resins having a glass transition (Tg) temperature  greater than 50xc2x0 C., amorphous polyamide or copolymer polyamide having a Tgxe2x89xa6120xc2x0 C., epoxies, amorphous polyurethanes and blends thereof with xe2x89xa760 wt % PET-G are especially useful as barriers to molecules having a diameterxe2x89xa70.40 nm, with PET-G and PMMA being especially preferred.
When preparing the essentially amorphous, non-chlorinated polymeric barrier films from blends such as exemplified above, the minor blend component need not be amorphous, but may be a semi-crystalline polymer. The definition of amorphous and semi-crystalline polymers can be found in the xe2x80x9cPolymer Science Dictionaryxe2x80x9d, 1989 edition, Elsevier Applied Science. It should also be understood that when the essentially amorphous, non-chlorinated polymeric barrier films are prepared from blends such as exemplified above, the major blend component, i.e., PET-G, constitutes xe2x89xa760 wt % of the blend. Typical examples of such blends are the following: 1) 70 to 95 wt % of a blend of PET-G and a SB copolymer; 2) 60 to 90 wt % of a blend of PET-G and a SBS block copolymer; 3) 70 to 96 wt % of a blend of PET-G and a MAH-g-EMA copolymer; 4) 70 to 96 wt % of a blend of PET-G and an ethylene-methyl acrylate-glycidyl methacrylate copolymer; 5) 70 to 96 wt % of a blend of PET-G and a MAH functionalized SEBS block copolymer; and 6) 70 to 96 wt % of a blend of PET-G and a SIS copolymer.
Blends of PET-g and an amorphous thermoplastic polyester resin such as APE-1 readily replace PET-G alone. Such blends have an APE-1 content that is desirably 0-100 wt %, preferably 10-80 wt % and more preferably 20-70 wt % and, conversely, a PET-G content that is desirably 100-0 wt %, preferably 90-20 wt % and more preferably 80-30 wt %. In each instance, the percentages total 100 wt %, with all percentages based on blend weight.
It has been found that it is critical that the essentially amorphous, non-chlorinated polymeric barrier films according to the present invention which are a barrier to molecules having a diameterxe2x89xa70.40 nm, also possess a H2S permeation rate of xe2x89xa660 cm3/m2-day.
The polymeric barrier films of the present invention which are barrier to molecules having a diameterxe2x89xa70.55 nm include, but are not limited to, films formed from Polymer List I and Polymer List II. Polymer List. II comprises: styrene-acrylonitrile (SAN) copolymers, blends of a SAN copolymer and an ethylene-styrene interpolymer (SAN-ESI), acrylonitrile-butadiene-styrene (ABS) terpolymer; impact-modified polymethyl methacrylate (PMMA-IM); polycarbonate (PC); impact-modified polycarbonate (PC-IM); and PC and ABS (PC/ABS) terpolymer alloy.
The polymeric barrier films of the present invention which are barrier to molecules having a diameterxe2x89xa70.70 nm include, but are not limited to, films formed from Polymer Lists I, II and III. Polymer List III comprises: polystyrenes, including general purpose polystyrenes (GPPS), high impact polystyrenes (HIPS), blends of GPPS and HIPS (GPPS/HIPS), blends of GPPS and a SB copolymer (GPPS/SB), blends of GPPS and ESI (GPPS/ESI), and blends of GPPS and SIS block copolymer (GPPS/SIS). Amorphous polyamides and co-polyamides having a Tg greater than 120xc2x0 C. are not within the scope of the present invention.
Examples of essentially amorphous, non-chlorinated polymeric barrier films prepared from blends of Polymer Lists II or III above may comprise the components of the blend in any proportion, but typically as follows: 1) 60 to 95 wt % of a blend of SAN copolymer and ESI; 2) 30 to 70 wt % of a blend of GPPS and HIPS; 3) 60 to 90 wt % of a blend of GPPS and SB copolymer; 4) 60 to 90 wt % of a blend of GPPS and ESI; and 5) 60 to 90 wt % of a blend of GPPS and SIS block copolymer.
The aforementioned ESI is a substantially random interpolymer comprising in polymerized form i) xe2x89xa7one alpha-olefin (xcex1-olefin) monomer and ii) xe2x89xa7one vinyl or vinylidene aromatic monomers and/or xe2x89xa7one sterically hindered aliphatic or cycloaliphatic vinyl or vinylidene monomers, and optionally iii) other polymerizable ethylenically unsaturated monomer(s).
The term xe2x80x9cinterpolymerxe2x80x9d is used herein to indicate a polymer wherein xe2x89xa7two different monomers are polymerized to make the interpolymer.
The term xe2x80x9csubstantially randomxe2x80x9d in the substantially random interpolymer resulting from polymerizing i) xe2x89xa7one olefin monomer and ii) xe2x89xa7one vinyl or vinylidene aromatic monomer and/or xe2x89xa7one or more sterically hindered aliphatic or cycloaliphatic vinyl or vinylidene monomers, and optionally iii) other polymerizable ethylenically unsaturated monomer(s) as used herein generally means that the distribution of the monomers of said interpolymer can be described by the Bernoulli statistical model or by a first or second order Markovian statistical model, as described by J. C. Randall in POLYMER SEQUENCE DETERMINATION, Carbon-13 NMR Method, Academic Press New York, 1977, pp. 71-78. Preferably, such substantially random interpolymers do not contain more than 15% of the total amount of vinyl or vinylidene aromatic monomer in blocks of vinyl or vinylidene aromatic monomer  greater than than 3 units. More preferably, the interpolymer is not characterized by a high degree of either isotacticity or syndiotacticity. This means that, in the carbon-13 NMR spectrum of the substantially random interpolymer, peak areas corresponding to the main chain methylene and methine carbons representing either meso diad sequences or racemic diad sequences should not exceed 75% of the total peak area of the main chain methylene and methine carbons. The subsequently used term xe2x80x9csubstantially random interpolymerxe2x80x9d or xe2x80x9cSRIPxe2x80x9d means a substantially random interpolymer produced from the above-mentioned monomers.
Suitable olefin monomers which are useful for preparing a SRIP include, for example, olefin monomers containing from 2 to 20 (C2-20), preferably from 2 to 12 (C2-12), more preferably from 2 to 8 (C2-8) carbon atoms. Particularly suitable are ethylene, propylene, butene-1, 4-methyl-1-pentene, hexene-1 or octene-1 or ethylene in combination with one or more of propylene, butene-1, 4-methyl-1-pentene, hexene-1 or octene-1. Most preferred are ethylene or a combination of ethylene with C3-8-xcex1-olefins. These alpha-olefins (xcex1-olefins) do not contain an aromatic moiety.
Other optional polymerizable ethylenically unsaturated monomer(s) include strained ring olefins such as norbornene and C1-10 alkyl or C6-10 aryl substituted norbornenes, with an exemplary interpolymer being ethylene/styrene/norbornene.
Suitable vinyl or vinylidene aromatic monomers, which can be employed to prepare a SRIP , include, for example, those represented by the following Formula I 
wherein R1 is selected from the group of radicals consisting of hydrogen and C1-4 alkyl radicals, preferably hydrogen or methyl; each R2 is independently selected from the group of radicals consisting of hydrogen and C1-4 alkyl radicals, preferably hydrogen or methyl; Ar is a phenyl group or a phenyl group substituted with from 1 to 5 substituents selected from the group consisting of halo, C1-4-alkyl, and C1-4-haloalkyl; and n has a value from zero to 4, preferably from zero to 2, most preferably zero. Particularly suitable such monomers include styrene and lower alkyl- or halogen-substituted derivatives thereof. Preferred monomers include styrene, xcex1-methyl styrene, the lower (C1-4) alkyl- or phenyl-ring substituted derivatives of styrene, such as for example, ortho-, meta-, and para-methylstyrene, t-butyl styrene, the ring halogenated styrenes, such as chlorostyrene, para-vinyl toluene or mixtures thereof. A more preferred aromatic monovinyl monomer is styrene.
The most preferred substantially random interpolymers are interpolymers of ethylene and styrene and interpolymers of ethylene, styrene and xe2x89xa7one C3-8 xcex1-olefin.
The SRIPs usually contain from 0.5 to 65, preferably from 1 to 55, more preferably from 2 to 50 mole percent (mol %) of xe2x89xa7one vinyl or vinylidene aromatic monomer and/or sterically hindered aliphatic or cycloaliphatic vinyl or vinylidene monomer and from 35 to 99.5, preferably from 45 to 99, more preferably from 50 to 98 mol % of xe2x89xa7one C2-20 aliphatic olefin. SRIPs can be prepared according to WO98/10014 and its US equivalents U.S. Pat. No. 5,703,187 and U.S. Pat. No. 5,872,201, the relevant teachings of which are incorporated herein by reference.
The barrier films of the present invention may contain one or more of the following additives: processing aids, such as fluoropolymers, silicones or siloxanes; inorganic fillers such as barium sulfate, calcium carbonate, mica, silica, silica gel, nanofillers and talc; slip additives such as fatty acid amides; antiblock additives; odor absorbers; humidity absorbers; molecular sieves; pigments; antistatic additives; antifog agents; antioxidants; UV stabilizers; dielectric heating sensitizing additives; pigments; colors; activated carbon; fragrance; nucleating agents, clarifiers; biocides and antimicrobial additives. The additives may optionally be encapsulated in microgranules. At least one outside layer of the film may be subjected to a surface treatment such as corona treatment or flame treatment or plasma treatment to increase its surface tension and improve its printability. Optionally, xe2x89xa7one surface of the film may also be coated with a thin layer of metal or metal oxide such as aluminum, aluminum oxide, or silicon oxide.
At least one surface of the film can be embossed or texturized to improve resistance to blocking, machinability, or handleability or to impart some performance benefit like softness, suppleness or appearance.
The essentially amorphous, non-chlorinated polymeric barrier films used in accordance with the present invention as barriers to odors and organic molecules may be used as single or monolayer films or as a component film of a multilayer film structure. Examples of the multilayer film structures comprise, but are not limited to, 2 to 7 layers and could, for example, take the form of A/B/D/C/D/E/F or A/B/C/B/A or A/B/C/D/E or A/B/C/D, or A/C/B/, or C/B, with the xe2x80x9cCxe2x80x9d layer being the essentially amorphous, non-chlorinated polymeric film layer of the present invention, with the other layers comprising adhesive, intermediate or skin layers. Multilayer film structures having more than one xe2x80x9cCxe2x80x9d layer, i.e., odor barrier layer, are also contemplated.
When the essentially amorphous, non-chlorinated polymeric films are used as single- or monolayer barrier films, the film has a thickness that depends upon the intended end-use of the film as well as the individual odor and organic compound barrier properties of the films. However, the thickness typically ranges from 5 to 50 micrometers (xcexcm), with from 10 xcexcm to 25 xcexcm being more typical, and from 12 xcexcm to 20 xcexcm being most typical. Although any essentially amorphous, non-chlorinated polymeric barrier film useful in the present invention may be used as a monolayer film, multilayer films of essentially amorphous, non-chlorinated polymers are also contemplated.
The monolayer barrier films of the present invention are prepared by conventional techniques, such as by extrusion, blowing, or casting, with extrusion being preferred. The barrier films of the present invention are also non-oriented films.
When not pigmented, not embossed and uncoated, the barrier films of the present invention are also transparent as defined by a haze value xe2x89xa645%, measured according to American Society for Testing and Materials (ASTM) test D1003. If haze is not important, the use of one or more of pigment addition, embossing, coating, or inclusion of other additives will not alter the scope of the present invention.
When the essentially amorphous, non-chlorinated polymeric barrier films are used as component films of a multilayer film structures, the essentially amorphous, non-chlorinated polymeric barrier film which provides the odor and organic compound barrier properties to the multilayer film structure typically has a thickness of from 2 xcexcm to 50 xcexcm, with from 3 xcexcm to 35 xcexcm being more typical and is not oriented.
Multilayer film structures typically include xe2x89xa7one layer formed from a polymer other than that used in the barrier film layer. Selection of such polymer(s) depends upon intended end uses for the multilayer structure. If freedom from chlorine is essential, all layers preferably lack chlorine. In applications where some chlorine is acceptable, such as packaging, protective clothing or soil fumigation, the multilayer film structures may also comprise chlorinated film layers in addition to the essentially amorphous, non-chlorinated polymeric barrier film of the present invention.
Polymers suitable for use in forming non-barrier layers include: LDPE, linear low density polyethylenes (LLDPE), ultra low density polyethylene (ULDPE), homogeneous EAO copolymers, HDPE, PP homo- or copolymers, rubber modified PP, low modulus PP homo- or copolymers, low crystallinity PP homo- or copolymers, syndiotactic PP homo- or copolymers, ethylene-propylene-diene monomer elastomer (EPDM), ethylene-polypropylene rubbers (EPF), substantially linear EAO copolymers, styrene-butadiene copolymers (SB or SBS), SEBS copolymers, styrene-isoprene copolymers (SI or SIS), ethylene-alkyl acrylate copolymers, such as, for example, ethylene-methyl acrylate (EMA), ethylene-butyl acrylate (EBA), ethylene-ethyl acrylate (EEA), ethylene-vinyl acetate (EVA), ethylene-acrylic acid copolymers (EAA), ionomer resins, elastomeric co-polyesters, ethylene-methyl acrylic acid copolymers (EMAA), polynorbornene, ESI, thermoplastic polyurethane (TPU), polyether-amide block copolymers, EVA-carbon monoxide copolymers (EVACO), MAH-modified polyethylene, maleic anhydride modified EVA, MAH-EMA, MAH-EBA, MAH-PP, glycidyl methacrylate modified EMA, glycidyl methacrylate modified EBA, glycidyl methacrylate modified EVA, polyamides, and blends thereof. One such blend includes an amorphous EAO polymer and a low crystallinity PP homo- or copolymer. EP 641,647 and its US equivalent U.S. Pat. No. 5,616,420 as well as EP 527 589, the relevant teachings of which are incorporated herein by reference, disclose, in part, blends of an amorphous polyolefin and a crystalline PP.
The use of copolymers of olefins and polar comonomers will additionally improve the high frequency (HF) sealing properties of the film.
Chlorinated polymers which can optionally be used together with the essentially amorphous, non-chlorine containing barrier films of the present invention include, for example, polyvinyl chloride (PVC), chlorinated polyethylene (CPE), poly(vinylidene chloride) (PVDC), PVDC/VC copolymers (PVDC/VC), PVDC/methyl acrylate copolymers (PVDC/MA), and mixtures thereof.
In a multilayer structure, the polymeric layers located immediately adjacent to the barrier layer will typically function as adhesive or tie layers, while other, non-adjacent layers typically function as intermediate or skin layers. The overall thickness of such a multilayer film structure depends upon the individual film or layer thicknesses. An individual film thickness depends upon a variety of factors, such as ease and cost of manufacturing a film of a given thickness, film physical and chemical properties, and the environment to which the multilayer film structure will be exposed. The overall thickness of such a multilayer film structure typically ranges from 20 xcexcm to 350 xcexcm, with from 30 xcexcm to 200 xcexcm being more typical, and from 40 xcexcm to 150 xcexcm being most typical.
When used in a TDDS application, such as a backing layer for a TDDS article or patch, the multilayer film structures typically have a two or three layer configuration with an overall thickness of 15 to 80 xcexcm, preferably 25 to 50 xcexcm. Such structures typically have an A/B or an A/C/D configuration. Layer A serves as a barrier layer and desirably comprises PET-G, APE-1, a blend of PET-G and APE-1, an amorphous thermoplastic polyester homo- or copolymer resin that has a Tg of at least 50xc2x0 C., and blends thereof such as a blend of one or both of PET-G and APE-1 with such a resin. Layer A has a thickness of 8-20 xcexcm, preferably 8-15 xcexcm. Layer B comprises an EVA copolymer with a vinyl acetate content of 15-30 wt %, an EMA copolymer with a methyl acrylate content of 15-30 wt % or an EBA copolymer with a butyl acrylate content of 15-30 wt %. Layer C includes all of the copolymers of Layer B plus MAH-g-EVA, MAH-g-EMA, MAH-g-EBA, glycidyl methacrylate grafted EVA, EMA or EBA, ethylene-acrylic ester-MAH terpolymers, ethylene-acrylic ester-glycidyl methacrylate terpolymers, ethylene-glycidyl methacrylate copolymers, SB copolymers, EVACO terpolymers, SI and SIS polymers, and blends thereof, together with. Layer C functions as a tie layer and has a thickness of 2-15 xcexcm. Layer D comprises any of the polymers identified above as suitable polymers for use in forming non-barrier layers other than the polyamides. The EVA, EBA and EMA, when used, preferably have a non-ethylene monomer content of 6-20 wt %. Any or all of layers B, C and D may include one or more of the slip and antiblock additives disclosed herein. In addition, any one or more of layers A-D may include an additive such as an antioxidant, a pigment, a ultraviolet light stabilizer or a processing aid. As with the other multilayer film structures, surface layer treatments may enhance one or more features of those structures having utility in TDDS applications.
Unless otherwise stated, as in the case of  less than 50, each range includes both endpoints that establish the range.
Conventional processes such as blowing or casting, co-extrusion, extrusion coating, extrusion lamination, or adhesive lamination may prepare the multilayer film structures of the present invention.
When used in a monolayer or a multilayer film structure as a barrier to molecules having a diameterxe2x89xa70.40 nm, the barrier films of the invention have a 3-methyl indole breakthrough time xe2x89xa72 hours (hrs), preferably 2-300 hrs, and a DEDS breakthrough time xe2x89xa78 minutes (min), preferably 20-1200 min. Such film structures serve as useful barriers to odors and organic molecules.
Table 1 provides representative barrier films useful in accordance with the present invention along with their respective 3-methyl indole and DEDS breakthrough times. Table 1 and succeeding Tables 2-4 are intended to be illustrative only and do not limit scope of the present invention in any way.
When used in a monolayer or a multilayer film structure as a barrier to molecules having a diameterxe2x89xa7to 0.40 nm, the barrier films of the invention have a 3-methyl indole breakthrough time xe2x89xa72 hrs, preferably 2-300 hrs, and an H2S breakthrough time xe2x89xa740 seconds (secs), preferably 40-250 secs. Such films serve as useful barriers to odors and organic molecules. Table 2 provides representative barrier films useful in accordance with the present invention along with their respective 3-methyl indole and H2S breakthrough times, wherein the films may be monolayer films or components in a multilayer film structure.
Yet, when used in a monolayer or a multilayer film structure as a barrier to molecules having a diameterxe2x89xa70.40 nm, the barrier films of the invention have a DEDS breakthrough time of 8 minutes (min), preferably 8-1200 min, and an H2S breakthrough time of 40 secs, preferably 40-250 secs. Such films serve as useful barriers to odors and organic molecules. Table 3 provides representative barrier films useful in accordance with the present invention along with their respective DEDS and an H2S breakthrough times, wherein the films may be monolayer films or components in a multilayer film structure.
Moreover, when used in a monolayer or a multilayer film structure as a barrier to odors, the barrier films have a 3-methyl indole breakthrough time xe2x89xa72 hrs, preferably 2-300 hrs, a DEDS breakthrough time xe2x89xa78 min, preferably 8-1200 min, and an H2S breakthrough time xe2x89xa740 secs, preferably 40-250 secs.
Table 4 provides representative barrier films useful in accordance with the present invention along with their respective 3-methyl indole, DEDS and an H2S break through times, wherein the barrier films may be monolayer films or components in a multilayer film structure.
In addition, depending upon the end-use of the polymeric barrier films of the present invention, it may be desirable that the polymeric barrier films of the present invention or multilayer polymeric film structure having a polymeric barrier film of the present invention as a component film exhibit additional properties.
For example, in addition to barrier properties, it is often desirable that polymeric films not emit noise when crumpled. In ostomy or incontinence applications, it is desirable that the ostomy or incontinence bags not emit noise. However, when crumpled, most polymeric films, especially multilayer polymer films comprised of individual polymeric film layers having different rigidities (i.e., modulus), emit noise. When a reduction in noise is desired, a xe2x80x9cnoise dampeningxe2x80x9d polymer may be blended, typically in amounts xe2x89xa725 wt %, with other (second) polymeric resins to form polymeric films of the present invention having barrier properties. Typically, these polymeric barrier films have a noise level xe2x89xa650 decibels (dBA) at one or more octave frequency bands between 1 kilohertz (kHz) and 16 kHz.
In addition, these polymeric resins having quietness properties may be included as component films in multilayer film structures to form multilayer film structures of the present invention having quietness properties. Typically, the noise dampening polymer will be present at xe2x89xa730 wt % in the layer and represent xe2x89xa725 wt % of the total film composition. Alternatively, a quiet polymeric film may be formed entirely from a noise-dampening polymer and included as a component film in a multilayer film structure of the present invention having quietness properties.
A quiet film according to the present invention will typically be used as a skin or an adhesive layer, but could also be used as an internal layer.
Typically, a noise dampening polymer will have a Tan xcex94 value xe2x89xa70.25 at a temperature within the range between xe2x88x925xc2x0 C. and 15xc2x0 C. or xe2x89xa70.32 in the temperature range of from xe2x88x9212xc2x0 C. to xe2x88x925xc2x0 C. Typical noise dampening polymers include, but are not limited to, polynorbornene polymers, low crystallinity PP homo- or copolymers having a heat of fusion  less than 50 Joules/gram (J/g), or syndiotactic PP homo- or copolymers, or atactic PP, or ESI resins. TPUs, EVA copolymers, EMA copolymers, EBA copolymers, PVC, and CPE are not within the scope of this invention with regard to use as noise dampening polymers.
The heat of fusion is determined by differential scanning calorimetry (D.S.C.). The equipment is calibrated using an indium standard. The heat of fusion of PP is determined using a heating rate of +10xc2x0 C./minute from xe2x88x9250xc2x0 C. to +220xc2x0 C. The heat of fusion is integrated between +25xc2x0 C. and +180xc2x0 C.
The noise dampening polymer can also be a polymeric composition obtained by blending a polymer which does not have a Tan xcex94 value xe2x89xa70.25 at a temperature within the range between xe2x88x925 and 15xc2x0 C. or xe2x89xa70.32 at a temperature within the range between xe2x88x9212xc2x0 C. and xe2x88x925xc2x0 C. with at least one of a compatible resin, plasticizer or tackifier that modifies its Tan xcex94 to such a value. One such blend is the blend of amorphous EAO polymer and a low crystallinity PP. homo- or copolymer noted above.
Examples of such Tan xcex94 modifications by blending are described in: The Viscoelastic Properties of Rubber Resin Blends: Parts I., II. and III., J. B. Class and S. G. Chu, Journal of Applied Polymer Science, Vol. 30, 805-842 (1985). Light and Stable Resins for Hot-melt Adhesives, P. Dunckley, Adhesives Age, November 1993. A Statistical Approach to Formulating Deep Freeze HMAS, W. J. HONIBALL, J. LEBEZ and al., Adhesives Ages, May 1997, pages 18-26. Tackifier Resins, James A. Schlademan, Handbook of Pressure Sensitive Adhesive Technology, Chapter 20, pages 527-544.
While certain polymers, such as the PP homopolymer and propylene copolymers (PCP-1, PCP-2 and PCP-3) shown in Table 5 below, may provide sufficient noise dampening performance to serve as a sole noise dampening polymer, others require augmentation with at least one other polymer or polymer modifier. In addition, blends of two or more resins serve as effective substitutes for such xe2x80x9csole noise dampening polymersxe2x80x9d. For example, a blend of an amorphous poly (xcex1-olefin) such as REXTAC(copyright) APAO2180, and a 2 melt flow rate random propylene/ethylene copolymer (2.3 wt % ethylene)) approximates one or more of the REXFLEX(copyright) flexible polyolefins (FPOs) shown in Table 5. Other blends of a high molecular weight (low melt flow rate) amorphous poly (xcex1-olefin) and a random propylene copolymer also provide effective results. One such blend is marketed by Ube Industries under the trade designation CAP-350. EP 527,589 and its US equivalent U.S. Pat. No. 5,468,807, and EP 641,647 and its US equivalent U.S. Pat. No. 5,616,420, the relevant teachings of which are incorporated herein, disclose such blends in an intermediate layer.
In addition, the use of a noise-dampening polymer or polymer composition is especially advantageous when it is included in a multilayer film structure that contains xe2x89xa7one other polymeric film layer which has a storage modulus (Gxe2x80x2) xe2x89xa72xc3x97104 Newtons per square centimeter (N/cm2 ) at room temperature. The polymeric film layers which have a storage modulus (Gxe2x80x2) xe2x89xa72xc3x97104 N/cm2 are typically prepared from amorphous thermoplastic polyesters, such as PET-G, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and other thermoplastic polyesters, EVOH, PC, polyvinyl alcohol (PVA), SAN, ABS, PMMA, SB copolymers, polyacrylonitrile, polyamides and co-polyamides, such as PA-6, PA-6,6, PA-11, and PA-12, amorphous polyamides, MXD6 polyamide, PVDC, PVDC/VC copolymers, PVDC/MA copolymers, polyhydroxy amino ether copolymers (PHAE), polyurethanes, epoxies, polyethylene naphthalate (PEN), syndiotactic polystyrene, and polystyrene.
Preferred commercially available amorphous thermoplastic polyesters include EASTART(trademark) PETG copolyester 6763 (Eastman Chemical, 1.27 g/cm3 density (ASTM D1505), and 10 cm3-mm/m2-24 hr-atmosphere oxygen permeability (ASTM D3985)) and Mitsui B-100 (Mitsui Chemicals Inc., 1.35 g/cm3 density, Tg of 62xc2x0 C.). The amorphous thermoplastic polyesters may be used singly or blended together. Using the PETG and B-100 resins by way of example, the blends desirably include from 0 to 100 wt % B-100 and conversely from 100 to 0 wt % PETG. Preferred blends include from 10 to 80 wt % B-100 and 90-20 wt % PETG. More preferred blends include 20 to 70 wt % B-100 and 80-30 wt % PETG. In all instances, the combined resins total 100 wt % and all percentages are based on blend weight. B-100 resin is an amorphous thermoplastic co-polyester resin supplied by Mitsui Chemicals Europe GmbH, it holds the chemical abstracts reference 87365-98-8. This is a copolymer of isophthalic acid (42xcx9c48 mole %), terephthalic acid (2xcx9c8 mole %), ethylene glycol ( greater than 40 mole % ) and 1.3-bis (2-hydroxyethoxy)benzene ( less than 10 mole %). The resin has a glass transition temperature of 62xc2x0 C. and a density of 1.35.
Typically, when the noise dampening polymer or polymer composition is used as part of a multilayer polymeric film structure, it may be present as any of the layers of the multilayer film structure although it is preferred to have it included in a skin layer or in a layer close to an outside surface of the structure.
Although described above in connection with polymeric films having barrier properties, it is understood that the polymeric films having noise dampening characteristics may also be useful in other applications where barrier properties are not required. Thus, another aspect of the present invention is the use of polymers or polymer compositions having a Tan xcex94 value xe2x89xa70.25 at a temperature within the range between xe2x88x925xc2x0 C. and 15xc2x0 C. or xe2x89xa70.32 at a temperature within the range of from xe2x88x9212xc2x0 C. to xe2x88x925xc2x0 C. as noise dampening polymeric films or quiet polymeric films.
Further, it may be desirable for the end use application to seal some of the multilayer films described previously, for example, to produce bags. In some instances, the seal strength of some skin polymer compositions may be too low when the film is sealed to itself or to other polymers. A higher seal strength may be obtained by adding a sealant layer as the outermost layer in the film, or by blending into the outermost layer of the film a polymer that improves the seal strength.